Method of alkylating betahaloethylbenzenes



United rates Patent @fifice 3,052,733 Patented Sept. 4, 1962 3,052,733 METHOD OF ALKYLATING BETA- HALOETHYLEENZENES George A. (blah, Stephen .l. Kuhn, and Harold W. Quinn, all of Sarnia, Qntario, Qanada, assignors to The Dow Chemical Company, Midland, Mich, a corporation of Delaware N Drawing. Filed June 6, 1969, Ser. No. 33,923 Claims. (will. 26tl-65l) This invention concerns a method and catalyst for alkylating beta-haloethylbenzenes having at least one replaceable hydrogen atom on a carbon atom of the aromatic nucleus with olefins to produce a corresponding beta-balm ethyl alkylated derivative. It relates more particularly to a method for alkylating beta-haloethylbenzene with aliphatic olefins to produce a corresponding beta-haloethyl alkyl benzene.

It is known to alkylate aromatic compounds by reaction of an olefin such as ethylene, propylene, butylene and the like with an aromatic compound such as benzene, toluene, chlorobenzene, etc., in the presence of a Friedel- Crafts catalyst.

It is known to prepare 1,3,5-ethylxylene by reaction of ethylbenzene and meta-xylene in the presence of hydrogen fluoride and titanium tetrafluoride as catalyst.

It is disadvantageous to alkylate haloalkyl aromatic compounds in the presence of a Friedel-Crafts catalyst, such as aluminum chloride, since the catalyst tends to interact with the haloalkyl group in the aromatic compound and results in low yields of product or undesired by-products.

It has now been discovered that haloalkyl aromatic compounds having at least one replaceable hydrogen atom on a carbon atom of the aromatic nucleus, and more particularly, beta-haloethylbenzenes, can readily be alkylated to produce a corresponding haloalkyl alkylated aromatic compound in good yield by reacting an olefin with the haloalkyl aromatic compound in the presence of a small but effective proportion, e.g. from 1 to 20 percent by Weight, based on the weight of the beta-haloethylbenzene initially used of a Friedel-Crafts type catalyst comprising a mixture of hydrogen fluoride and titanium tetrafluoride in proportions corresponding to at least 0.5 gram molecular proportion or more of the hydrogen fluoride per gram molecular proportion of the titanium tetrafluoride.

It has further been found that a mixture of hydrogen fluoride and titanium tetrafluoride in proportions of at least 0.5 gram mole, preferably from 1 to 10 moles, of

the hydrogen fluoride per gram mole of the titanium tetrafluoride, is a most effective catalyst for alkylating betahaloethylbenzenes with olefins to produce a corresponding beta-haloethyl alkylbenzene.

It has been found that alkylation of the aromatic nucleus of beta-haloethyl aromatic compounds with olefins can readily, rapidly and efiiciently be carried out in the presence of a catalyst comprising hydrogen fluoride and titanium tetrafluoride with little, if any, reaction of the side chain halogen atom to form decomposition products or undesired by-products, and at atmospheric or substantially atmospheric pressure.

Broadly, the present invention comprises alkylating a haloalkyl aromatic compound with an olefin while in contact with a catalyst comprising anhydrous or substantially anhydrous hydrogen fluoride and titanium tetrafluoride or a complex of the hydrogen fluoride, titanium tetrafluoride and the haloalkyl aromatic compound starting material.

More specifically, the invention comprises alkylating a beta-haloethylbenzene with an olefin, preferably a monoethylenically unsaturated aliphatic olefin containing from 2 to 12 carbon atoms in the molecule, in the presence of,

or in contact with, a catalyst comprising hydrogen fluoride and titanium tetrafluoride as hereinbefore stated.

The haloalkyl aromatic compounds to be alkylated can be any haloalkyl aromatic compound having at least one replaceable hydrogen atom on a carbon atom in the aromatic nucleus and a halogen atom in the beta position in the alkyl side chain, such as beta-chloroethylnaphthalene, beta-bromoethyldiphenyl, beta-bromoethyl- Xylene, beta-chloroethylethylbenzene, beta-chloroethylbenzene, beta-bromoethylbenzene, beta-chloroethyltoluene, beta-bromoethyltoluene, beta-bromoethylxylene, betachloroethylxylene, beta-fluoroethylbenzene, beta-fluoroethyltoluene, beta-fluoroethylxylene, beta-iodoethylbenzene or beta-fluoroethyl ethylbenzene. It may be mentioned that alkylation of the iodine-containing compounds, e.g. beta-iodoethyl-benzene, results in somewhat lower yields of the corresponding beta-iodoethyl alkylbenzene because of the greater tendency of the iodine-containing compounds and the alkylated derivatives to decompose, and for this reason the invention is advantageously employed in the alkylation of the bromo-, chloro-, and fluoroalkylaromatic compounds, preferably the beta-chloroethyl-, beta-bromoethyl-, and beta-fluoroethylaromatic compounds of the benzene series, i.e. containing six carbon atoms in the aromatic nucleus.

The olefins to be employed in the alkylating reaction can be any monoethylenically unsaturated olefin contain.- ing a double bond between vicinal carbon atoms in an aliphatic chain. Examples of suitable olefins are styrene, vinyltoluene, vinylxylene, isopropyl styrene, ethylvinylbenzene, alpha-methylstyrene, alpha-ethylstyrene, and aliphatic hydrocarbons such as ethylene, propylene, isobutylene, butene-l, butene-2, isopentene, pentene-l, hex

ene-l, isohexene, heptene, octene-l, 2-ethylbutene-l, nonene, decene, undecene and dodecene and the like. The aliphatic olefins containing from 2 to 12 carbon atoms are preferred.

The invention is described more particularly herein.- after with reference to the alkylation of beta-haloethyls benzenes with aliphatic olefins, it being understood that the alkylation of the halo-alkyl aromatic compounds with olefins as hereinbefore described is equally applicable in the practice of the invention.

The proportions of the olefin and the beta-haloalkyl aromatic compound can be varied over wide limits, but is generally Within the range of from about 0.25 to 1.5 gram molecular proportions of the olefin per gram mole of the beta-haloalkyl aromatic starting material in order to obtain products which consist predominantly of the mono-substituted alkylation product, although greater proportions of the olefin can be used.

It is important that the catalyst contain the hydrogen fluoride in proportions corresponding to at least 0.5, preferably from 5 to 20, gram molecular proportions of the hydrogen fluoride per gram molecular proportion of the titanium tetrafluoride therein. The catalyst can be employed in amounts of from about 1 to 20 percent by weight of the beta-haloethylbenzene initially used.

The alkylation reaction can be carried out at temperatures between 80 and 35 C., preferably from 20 to 30 C., and at atmospheric or substantially atmospheric pressure, and in any suitable reaction vessel such as a reaction vessel made of polytetrafluoroethylene or polyethylene or an iron or steel vessel lined with such polymeric material.

In practice, a charge of the beta-haloethylbenzene to be alkylated is placed in a suitable reaction vessel, together with the titanium tetrachloride in the desired proportion. The mixture is stirred and maintained at a desired tem-' perature While introducing anhydrous or substantially anhydrous hydrogen fluoride into the liquid in the desired amount. Usually the addition of the hydrogen fluoride results in the formation of a yellow or yellow brown colored complex layer or dispersion. Thereafter, the olefin is added, preferably at about the rate it is consumed in the reaction while maintaining the resulting mixture withobtained 46 grams of unreacted beta-chloroethylbenzene boiling at 60-85 C. at 5 millimeters absolute pressure, 125 grams of beta-chloroethyl tert.-butylbenzene boiling at 97-102 C. at 4 millimeters and 9 grams of higher in the temperature range herein specified until the desired 5 boiling residue. The conversion was 67 percent. The amount of the olefin has been added. The product can yield of beta-chloroethyl tert.-butylbenzene was 94.5 perbe recovered in usual ways such as by pouring the recent based on the beta-chloroethylbenzene consumed in action mixture onto crushed ice or mixing it with cold the reaction. water to decompose the catalyst, then separating and Example 3 washing the organic layer, with water or an aqueous 10 A Charge of 62 grams (05 mole) of betafiuoroethyb sohinon such as an aqueolis 5 Weight liercent Sohmon i benzene, together with 3 grams of titanium tetrafluoride sodmln carbonat? or i hydroxlde' The Orgamc was placed in a reaction vessel made of polytetrafluorolayer is usually dned, then distilled to separate and recover ethylene and equipped with a reflux condenser and Stirren the beta'haloeihyl alkylbenze. product The mixture was stirred and cooled to a temperature of followmg. examples Illustrate Y m which the about 4 C. and 1 0 grams of anhydrous hydrogen fluoride pnnmpk of the Y EW P been apphed but are not was added. Thereafter, isobutylene was bubbled into to be construed as hmmng Its Scope the liquid for a period of 0.5 hour while stirring and main- Example I taining it at temperatures between 5 and 10 C. The reaction mixture was poured onto crushed ice and the A charge of 226 grams (1.23 moles) of betaabromoorganic layer was washed with water and separated. It ethylb nzen g h r ith g a s 0 ti ani m t tr was dried with anhydrous sodium sulfate and was distilled. fluoride (TiF was placed in a reaction vessel made of There was obtained 23 grams of unreacted beta-fluoropolytetrafluoroethylene and equipped with a reflux conethylbenzene boiling at 52-58 C. at 6 millimeters a-bdenser and stirrer. The mixture was stirred and mainsolute pressure, 28 grams of beta-fluoroethyl tertHbutyltained at about 4 C. by cooling the reaction vessel in a benzene boiling at 82-86 C. at 4 millimeters and 25 [bath of ice and water. A charge of 20 grams of hydrogen grams of higher boiling residue. The conversion was 63 [fluoride was bubbled into the liquid. A yellow-brown percent. The yield of beta-fluoroethyl tert.-butylbenzene colored complex layer was formed. Isobutylene was Was 49.5 percent based on the beta-fluoroethylbenzene bubbled into the liquid over .a period of one hour while 30 consumed in the reaction. stirring and maintaining the mixture at temperatures be- Emm le 4 tween 5? and 10 C.' until a total of about 41.5 grams p (0.74 mole) of isobutylene was added. The reaction mix- In each of a series of experiments, a charge of one ture was poured onto crushed ice and the organic layer gram molecular proportion of a beta-haloethylbenzene as was washed with Water and was separated and dried with identified in the following table was reacted with 0.33 anhydrous calcium chloride. The dried organic layer was gram 016 f an l fin as stated in the table While in distilled. There was obtained 110 grams (0.6 mole) of contact with a catalyst mixture consisting of 5 grams of unreacted beta-'bromo-ethylbenzene boiling at 98 C. at titanium tetrafluofide and 10 gram 111016) of y 14 millimeters absolute pressure, 128 grams (0.53 mole) gen fluoride employing procedure similar to that described of beta-bromoethyltertybutylbenzene boiling at 120 C.- 40 in Example 1. The product was separated and recovered 135 C. at 11 millimeters, and 16 grams of higher boilby procedure similar to that employed in said example. ing re idue, Th yield of beta-bromoethyl tert -buty1- The table identifies the experiments, names the beta-haloben-zene was .84 percent based on the beta-bromoethylethylbenzene and the olefin employed in the reaction, and benzene consumed in the reaction. gives the reaction conditions of time and temperature. The table names the beta-haloethyl alkyl benzene product, Examplez gives its boiling range and the percent yield of said A charge of 140.5 grams (1 mole) of beta chloroethylproduct, based on the weight of the beta-haloethyl-benzene benzene, together with 5 grams of titanium tetrafluoride, starting material consumed in the reaction.

TABLE Starting Materials Reaction Product Conditions Run N0. flHaloethylbenzene Olefin Temp, Time, B.P.,C Yield, 00. Hrs. Kind mm. Per- Kind gm. Kind gm. t

mole mole B-chloroethy1benzene 1 ethylene 0. 33 10 2 B-chloroethyl ethylben- 80-81/5 53 do 1 propylene. 0. 33 5 1.5 flilil roethyl isopro- 89-91/5 72 pylbenzene. do 1 is0buty1ene 0. 33 10 2 fl-chloroethyl tert.-bn- 97102/4 67 tyl benzene. B-bromoethylbenzene- 1 ethylene 0. 33 O 2 fl-bromoethyl ethyl ben- 92-.93/4 58 V 7 do 1 propy1ene 0. 33 15 1 fl-lgid ioethylisopropyl- 101-102/5 -71 I6 do 1 isobutylene. 0.33 5 l fibrdiiifdlshyl tert.-bu- 117-119/5 84 tyl benzene. 7 fl-fiuoroethylbenzene 1 propylene.-. 0. 33 0 1.5 fl-guoroethyl isopropyl 78-79/4 63 8 do 1 isobutylene 0.33 O 1.5 fl-flr i di ei hyl tert.-buty1 84-85/4 benzene.

was placed in a reaction vessel made of polyethylene and 70 We claim:

equipped withareflux condenser and stirrer, and 19 grams of anhydrous hydrogen fluoride was added. Isobutylene was added and reacted with the beta-chloroethylbenzcne employingprocedure similar to that employed in Example 1. The organic layer was dried and distilled. There was 1. A method for making a beta-haloalkyl alkaryl compound which comprises contacting a beta-haloalkyl aromatic compound having at least one replaceable hydrogen atom on a carbon atom of the aromatic nucleus with a monoethylenically unsaturated olefin having a double 'bond between vicinal carbon atoms in an aliphatic radical while in admixture with from 1 to 20 percent by weight, based on the weight of the beta-haloalkyl aromatic compound, of an alkylating catalyst comprising hydrogen fluoride and titanium tetrafluoride in proportions corresponding to from 0.5 to 20 gram molecular proportions of the hydrogen fluoride per gram mole of the titanium tetrafiuoride at temperatures between -80 C. and 35 C.

2. A method according to claim 1, wherein the betahaloalkyl aromatic compound is a beta-haloethylbenzene.

3. A method according to claim 1, wherein the monoethylenically unsaturated olefin is an aliphatic olefin containing from 2 to 12 carbon atoms in the molecule.

4. A method according to claim 1, wherein the betahaloalkyl aromatic compound is beta-chloroethylbenzene and the monoethylenically unsaturated olefin is ethylene.

5. A method according to claim 1, wherein the betahaloalkyl aromatic compound is beta-chloroethylbenzene and the monoethylenically unsaturated olefin is propylene.

6. A method according to claim 1, wherein the betahaloalkyl aromatic compound is beta-chloroethylbenzene and the monoethylenically unsaturated olefin is isobutylene.

7. A method according to claim 1, wherein the betahaloalkyl aromatic compound is beta-bromoethylbenzene and the monoethylenically unsaturated olefin is ethylene.

8. A method according to claim 1, wherein the betahaloalkyl aromatic compound is beta-bromoethylbenzene and the monoethylenically unsaturated olefin is propylene.

9. A method according to claim 1, wherein the betahaloalkyl aromatic compound is beta-fluoroethylbenzene and the monoethylenically unsaturated olefin is propylene.

10. A method for making a beta-fluoroethyl alkylbenzene which comprises contacting beta-fluoroethylbenzene with isobutylene While in admixture with from 1 to 20 percent by Weight, based on the weight of the betafluoroethylbenzene, of an alkylating catalyst comprising hydrogen fluoride and titanium tetrafluoride in proportions c-onrespondingto from 1 to 20 gram molecular proportions of the hydrogen fluoride per gram mole of the titanium tetrafluoride at temperatures between 80 C. and C., and separating beta-fluoroethyl tert.-butylbenzene from the reacted mixture.

References Cited in the file of this patent UNITED STATES PATENTS 2,275,312 Tinker et al. Mar. 3, 1942 2,683,760 McCauley et a1. July 13, 1954 2,889,377 'Floria June 2, 1959 2,998,460 Olah et a1. Aug. 29, 1961 

1. A METHOD FOR MAKING A BETA-HALOALKYL ALKARYL COMPOUND WHICH COMPRISES CONTACTING A BETA-HALOALKYL AROMATIC COMPOUND HAVING AT LEAST ONE REPLACEABLE HYDROGEN ATOMS ON A CARBON ATOM OF THE AROMATIC NUCLEUS WITH A MONOETHYLENICALLY UNSATURATED OLEFIN HAVING A DOUBLE BOND BETWEEN VICINAL CARBON ATOMS IN AN ALIPHATIC RADICAL WHILE IN ADMIXTURE WITH FROM 1 TO 20 PERCENT BY WEIGHT, BASED ON THE WEIGHT OF THE BETA-HALOALKYL AROMATIC COMPOUND, OF AN ALKYLATING CATALYST COMPRISING HYDROGEN FLUORIDE AND TITANIUM TETRAFLUORIDE IN PROPORTIONS CORRESPONDING TO FROM 0.5 TO 20 GRAM MOLECULAR PROPORTIONS OF THE HYDROGEN FLUORIDE PER GRAM MOLE OF THE TITANIUM TETRAFLUORIDE AT TEMPERATURES BETWEEN -80*C. AND 35*C. 